Data transmission device, radio reception device, radio transmission method, and radio reception method

ABSTRACT

A radio transmission device capable of improving the reception error rate characteristics of a receiver. In this device, an FFT (Fast Fourier Transform) unit ( 102 ) subjects a transmission signal to an FFT operation, in which a signal in a time domain is converted into a signal in a frequency domain. A control unit ( 103 ) controls the transmission power of the FFT-operated transmission signal in the frequency domain. An IFFT (Inverse Fast Fourier Transform) unit ( 104 ) subjects the transmission signal having its transmission power controlled, to an IFFT operation, in which an inverse conversion is made into a signal in the time domain. A transmission RF unit ( 106 ) transmits the IFFT-operated transmission signal on a single carrier.

TECHNICAL FIELD

The present invention relates to a radio transmission apparatus, radioreception apparatus, radio transmission method and radio receptionmethod, and, more particularly, to a radio transmission apparatus, radioreception apparatus, radio transmission method and radio receptionmethod for use in single carrier transmission systems with frequencydomain equalization.

BACKGROUND ART

Single carrier transmission systems with frequency domain equalizationhave been studied, in recent years, for use in next-generation mobilecommunication systems. In single carrier transmission systems withfrequency domain equalization, data symbols arranged in the time domainis transmitted on single carriers. A receiver executes frequency domainequalization processing to equalize, in a frequency domain, distortionsof a signal on a transmission path. By the frequency domain equalizationprocessing, these distortions are corrected. More specifically, achannel estimation value is calculated for each frequency in thefrequency domain and weight is assigned to equalize distortions of thepropagation path for each frequency. Then, received data is demodulated(see Non-Patent Document 1, for instance).

Non-patent Document 1: “Frequency Domain Equalization for single-CarrierBroadband Wireless Systems”, IEEE Communications Magazine, April 2002,pp. 58-66.

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However, in the conventional single carrier transmission system withfrequency domain equalization as described above, there are cases wherereception power for any of the frequencies within the bandwidth in usemay drop drastically as compared to transmission power, due to theinfluence of the propagation path having characteristics that vary foreach frequency. In this case, the transmission power allocated to thetransmitted signal is wasted by the amount of such drop. For thisreason, there is a certain limit to improving reception error ratecharacteristics of the receiver.

It is therefore an object of the present invention to provide a radiotransmission apparatus, radio reception apparatus, radio transmissionmethod and radio reception method capable of improving reception errorrate characteristics of a receiver.

Means for Solving the Problem

In accordance with one aspect of the present invention, a radiotransmission apparatus employs a configuration having: a conversionsection that converts a signal in a time domain to a signal in afrequency domain; a control section that controls a transmission powerof the converted signal in the frequency domain; an inverse conversionsection that inversely converts the transmission power controlled signalto a signal in the time domain; and a transmission section thattransmits the inversely converted signal on a single carrier.

In accordance with one aspect of the present invention, a radioreception apparatus employs a configuration having: a conversion sectionthat converts a signal in a time domain transmitted on a single carrierto a signal in a frequency domain; a determining section that determinesan algorithm for frequency domain equalization processing to which theconverted signal is to be subjected; a generation section that generatesfrequency domain equalization algorithm information showing thedetermined algorithm; and a transmission section that transmits thegenerated frequency domain equalization algorithm information to a radiotransmission apparatus.

In accordance with one aspect of the present invention, a radiotransmission method includes: a conversion step of converting a signalin a time domain to a signal in a frequency domain; a control step ofcontrolling a transmission power of the converted signal in thefrequency domain; an inverse conversion step of inversely converting thesignal with the transmission power controlled to the signal in the timedomain; and a transmission step of transmitting the inversely convertedsignal on a single carrier.

In accordance with one aspect of the present invention, a radioreception method includes: a conversion step of converting a signal in atime domain transmitted on a single carrier, to a signal in a frequencydomain; a determination step of determining an algorithm for frequencydomain equalization processing to which the converted signal is to besubjected; a generation step of generating frequency domain equalizationalgorithm information showing the determined algorithm; and atransmission step of transmitting the generated frequency domainequalization algorithm information to a radio transmission apparatus.

Advantageous Effect of the Invention

The present invention improves reception error rate characteristics of areceiver.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a configuration of a radiotransmission apparatus according to embodiment 1 of the presentinvention;

FIG. 2 is a block diagram showing a configuration of a radio receptionapparatus according to embodiment 1 of the present invention;

FIG. 3 is a flowchart for explaining the operations of a control sectionin a radio transmission apparatus according to embodiment 1 of thepresent invention;

FIG. 4 is a diagram for explaining a coefficient calculation processingaccording to embodiment 1 of the present invention;

FIG. 5A is a diagram showing one example of weighting in transmissionpower control according to embodiment 1 of the present invention;

FIG. 5B is a diagram showing another example of weighting intransmission power control according to embodiment 1 of the presentinvention;

FIG. 5C is a diagram showing yet another example of weighting intransmission power control according to embodiment 1 of the presentinvention; and

FIG. 6 is a block diagram showing a configuration of a radiotransmission apparatus according to embodiment 2 of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings.

Embodiment 1

FIG. 1 is a block diagram showing a configuration of a radiotransmission apparatus according to embodiment 1 of the presentinvention. FIG. 2 is a block diagram showing a configuration of a radioreception apparatus that carries out radio communication with radiotransmission apparatus 100 of FIG. 1.

The present invention can be applied to mobile communication systemswhere a plurality of frequencies are included in the single-carrier bandin use. However, in the present embodiment and the subsequentembodiments, the number of frequencies included in the band is assumedto be four, for ease of explanation. Also, in the present embodiment andthe subsequent embodiments, each frequency (or each frequency band)within the single-carrier band in use can be used as a virtualsubcarrier in the communication band. Further, it can also be used as asub-band obtained by segmenting the communication band.

Radio transmission apparatus 100 has: modulation section 101 thatmodulates a transmission signal; FFT section 102 that subjects themodulated transmission signal to FFT (Fast Fourier Transform)processing, in which a signal in a time domain is converted to a signalin a frequency domain; control section 103 that controls, in a frequencydomain, a transmission power of the FFT-processed transmission signal;IFFT section 104 that subjects the transmission signal, having itstransmission power controlled, to IFFT (Inverse Fast Fourier Transform)processing, in which the signal in the frequency domain is inverselyconverted to a signal in the time domain; CP processing section 105 thatadds a CP (Cyclic Prefix) to the IFFT-processed transmission signal, ata predetermined position thereof; transmission RF section 106 thatsubjects the transmission signal with the CP added thereto, topredetermined transmission radio processing including D/A conversion,up-conversion, and the like, and transmits the transmission signalsubjected to the transmission radio processing, on a single carrier, viaantenna 107; and reception RF section 108 that receives the radio signalvia antenna 107 and subjects the received radio signal to predeterminedreception radio processing including down-conversion, D/A conversion andthe like.

Also, control section 103 has multiplication sections 111 and 112,transmission power control section 113, weighting factor control section114 and weighting factor deriving section 115. Weighting factor derivingsection 115 has propagation path information extraction section 116,algorithm information extraction section 117 and error ratecharacteristic prediction section 118.

In weighting factor deriving section 115, algorithm informationextraction section 117 extracts frequency domain equalization algorithminformation (described later), from the signal that has been subjectedto the reception radio processing (hereinafter referred to as “receivedsignal”). Propagation path information extraction section 116 extracts,from the received signal, propagation path information (describedlater). Error rate characteristic prediction section 118 predicts thereception error rate characteristic of radio reception apparatus 150 inthe case where the signal, with its transmission power controlled, istransmitted, in accordance with the extracted frequency domainequalization algorithm information and propagation path information, andderives a weighting factor for weighting the transmission power control,by using the results of the prediction.

The extracted propagation path information and the derived weightingfactor are respectively controlled by transmission power control section113 and weighting factor control section 114, and are multiplied by eachother at multiplication section 112. The transmission power of theFFT-processed transmission signal is corrected by multiplication section111, for each frequency, so as to take a value obtained as a result ofthe multiplication by multiplication section 112.

Radio reception apparatus 150 shown in FIG. 2 has antenna 151, receptionRF section 152, CP removing section 153, FFT section 154, channelestimation section 155, frequency domain equalization section 156, IFFTsection 157, demodulation section 158, algorithm determining section159, algorithm information generation section 160, transmission RFsection 161 and propagation path information generation section 162.

Reception RF section 152 receives the radio signal via antenna 151 andsubjects this signal to a predetermined reception radio processingincluding down-conversion, A/D conversion and the like. CP removingsection 153 removes the CP that has been added to a predeterminedposition of the received signal. FFT section 154 subjects the receivedsignal, having its CP removed, to an FFT processing in which the signalin a time domain is converted to a signal in a frequency domain. Channelestimation section 155 executes channel estimation using a pilot signalfrom among the FFT-processed received signals.

Algorithm determining section 159 determines an algorithm of thefrequency domain equalization processing in accordance with aninstruction from an upper layer and reports the determined algorithm tofrequency domain equalization section 156 and algorithm informationgeneration section 160. The MMSE (Minimum Mean Square Error) scheme, theMRC (Maximal Rate Combining) scheme, the ORC (Orthogonality RestoringCombining) scheme, the EGC (Equal Gain Combining) scheme and the like,for example, are given as algorithms for the frequency domainequalization processing.

Frequency domain equalization section 156 subjects the FFT-processedreceived signal to frequency domain equalization processing, inaccordance with the reported algorithm and using the channel estimationresult.

IFFT section 157 subjects the frequency domain equalization-processedreceived signal to IFFT processing in which the signal in the frequencydomain is inversely converted to a signal in the time domain.Demodulation section 158 demodulates the IFFT-processed received signal.

Algorithm information generation section 160 generates frequency domainequalization algorithm information that shows the determined algorithmand which reports the determined algorithm to radio transmissionapparatus 100. Propagation path information generation section 162generates, from the received signal having its CP removed, propagationpath information for reporting the power gain for each frequency on thepropagation path to radio transmission apparatus 100.

Transmission RF section 161 subjects the generated frequency domainequalization algorithm information and the propagation path informationto predetermined transmission radio processing including D/A conversion,up-conversion and the like, and transmits the frequency domainequalization algorithm information and the propagation path informationwhich have been subjected to the transmission radio processing, to radiotransmission apparatus 100, via antenna 151.

Next, the transmission power control operation in control section 103 ofradio transmission apparatus 100 will be explained. FIG. 3 is aflowchart for explaining the operation of control section 103.

First, in step S1, propagation path information extraction section 116extracts the propagation path information from the received signal.Here, the propagation path information is shown by Hk (k is thefrequency number) as a scalar value. Also, algorithm informationextraction section 117 extracts the frequency domain equalizationalgorithm information from the received signal.

Next, in step 2, error rate characteristic prediction section 118predicts the error rate characteristic of radio reception apparatus 150at the time a transmission signal having its transmission powercontrolled, is transmitted. As a result of this prediction, a functionthat shows the predicted reception error rate ER is acquired. In otherwords, if the weighting factor is shown by W as a scalar value, thepredicted reception error rate ER is expressed by the following equation(1).ER=f(W)   (1)

Thus, since the function f(W) which is the base for deriving theweighting factor W for use is acquired in accordance with the frequencydomain equalization algorithm information transmitted from radioreception apparatus 150, it is possible to derive a weighting factor Wusing a function that is most suitable for the algorithm shown in thefrequency domain equalization algorithm information.

Next, in step S3, error rate characteristic prediction section 118calculates the weighting factor W for use in transmission power control,by means of the above equation (1). In other words, a predeterminedoptimization technique is applied to function f(W) of equation (1) tocalculate a weighting factor W_(MIN) _(—) _(ER) for optimizing thereception error rate ER. More specifically, a weighting factor W_(MIN)_(—) _(ER) that makes the reception error rate ER a minimum valueMIN_ER, is calculated, as shown in FIG. 4. In other words, in this case,the weighting factor W_(MIN) _(—) _(ER) is calculated by the operationof W=argmin(f(W)).

Here, FIG. 4 shows one example of the function f(W). If, for instance,the weighting coefficient W of the illustrated function f(W) is set toW=0, the transmission power of the transmission signal is not at allcontrolled in the frequency domain, as shown in FIG. 5A. Also, if, forinstance, the weighting factor W is set to a suitable value in the range0<W<1, the transmission power of the transmission signal is controlledby a value lower than the gain of the signal on the propagation path, asshown in FIG. 5B, and thus, the predicted reception error rate ERdecreases as compared to the case where the transmission power controlis not carried out. Further, if, for instance, the weighting factor W isset to W=1, the transmission power of the transmission signal iscontrolled by the same value as the gain of the signal on thepropagation path, as shown in FIG. 5C. In other words, maximum ratiotransmission is carried out. The reception error rate ER predicted inthis case rises as compared to the case where the weighting factor W isset to a suitable value in the range of 0<W<1.

Next, the calculated weighting factor W_(MIN) _(—) _(ER) is reported toweighting factor control section 114. Weighting factor control section114 controls the reported weighting factor W_(MIN) _(—) _(ER) andoutputs it to multiplication section 112. Also, propagation pathinformation Hk extracted in step S1 is reported to transmission powercontrol section 113. Transmission power control section 113 controls thepropagation path information Hk and outputs it to multiplication section112.

Next, in step S4, multiplication section 112 multiplies the propagationpath information Hk by the weighting factor W_(MIN) _(—) _(ER). By thismultiplication, the transmission power control is weighted. Also, asresult of the multiplication, a transmission power Pk associated witheach frequency within the band in use is obtained, as shown in thefollowing equation (2).Pk=W _(MIN) _(—) _(ER) ×Hk   (2)

In step S5, multiplication section 112 corrects the transmission powerof the transmission signal in the frequency domain by means of thetransmission power Pk.

According to the present embodiment, in radio transmission apparatus100, the signal in a time domain, transmitted on a single carrier, isconverted to a signal in a frequency domain, and its transmission poweris controlled in a frequency domain, so that the transmission powerallocated to the signal to be transmitted on a single carrier can beeffectively used, and the reception error rate of radio receptionapparatus 150 can be improved.

Also, according to the present embodiment, since in radio receptionapparatus 150, information showing a determined frequency domainequalization algorithm is generated and transmitted, it is possible toreport the frequency domain equalization algorithm to radio transmissionapparatus 100, and radio transmission apparatus 100, which derives theweighting factor W from the function f(W), can acquire a function f(W)that is most suitable for this algorithm, and, as a result, thereception error rate characteristic can be improved. In other words, itis possible to improve the reception error rate characteristic by onlyadding a simple configuration for reporting the frequency domainequalization algorithm to radio transmission apparatus 100, and withoutadding any particular configuration to the reception system (receptionRF section 152, CP removing section 153, FFT section 154, channelestimation section 155, frequency domain equalization section 156, IFFTsection 157 and demodulation section 158) itself of radio receptionapparatus 150.

Further, according to the present embodiment, the coefficient W isderived using the function f(W) showing the reception error rate ERpredicted when a signal having its transmission power controlled istransmitted to radio reception apparatus 150, so that it is possible tocarry out a most suitable transmission power control in consideration ofthe signal distortions caused by the transmission power control.

In other words, in the present embodiment, the weighting factor W forweighting the transmission power control is searched in accordance withthe predictions for the fluctuation of the reception error rate ER. Inthis way, it is possible to prevent the transmission power from beingexcessively corrected.

By comparison, in one example of a technology for transmission powercontrol in multicarrier transfer, for instance, the transmission poweris controlled in the frequency domain at a level which is always thesame as the fluctuations of the propagation path. In other words,maximum ratio transmission is carried out. In this case, the receptionpower at each frequency on the receiver-side appears as fluctuations ofthe squares of the fluctuations of the propagation path. Thissignificant increase of power fluctuations in a frequency domain maybecome, in single carrier transmission, a factor that leads todeteriorated reception error rates. In other words, there may be caseswhere the deterioration of error rate characteristics caused bytransmission power control is greater than the effects of the error ratecharacteristic improvement by maximum ratio transmission. However, inthe present embodiment, by predicting the fluctuations of the error ratecharacteristic due to the transmission power control, it is possible toderive an optimal weighting factor W that makes the deterioration oferror rate characteristic caused by the transmission power control isless than the effects of error rate characteristic improvement, and, asa result, the reception error rate ER of the radio reception apparatus150 can be reliably improved.

Also, according to the present embodiment, the transmission power can becontrolled by using the weighting factor W_(MIN) _(—) _(ER) thatminimizes the predicted reception error rate ER, so that the receptionerror rate of the radio reception apparatus 150 can be minimized.

Further, according to the present embodiment, an optimal transmissionpower can be obtained from the weighting factor W that is commonly setbetween the frequencies included in the single-carrier band, and thepropagation path information Hk, so that optimal weighting of thetransmission power control is possible.

In this embodiment, as described above, the weighting factor W is set toa common value between frequencies. However, the weighting factor may beset individually for each frequency (i.e., a weighting factor Wassociated with each frequency may be derived).

Also, in the present embodiment, the weighting factor W is derived byusing a function of reception error rate ER. However, the derivationmethod of the weighting factor W is not limited to the above method, butit may also be a method based on other suitable parameters. Othersuitable parameters may include existing or new information to betransmitted from radio reception apparatus 100, or, existing or newinformation to be measured, calculated or set by radio transmissionapparatus 100.

Also, in the present embodiment, FFT processing is adopted for theprocessing for converting a signal in a time domain to a signal in afrequency domain, and IFFT processing is adopted for the processing forinversely converting the signal in the frequency domain to a signal in atime domain. In addition, applicable conversion processing is notlimited to FFT processing alone, but other suitable processingincluding, for instance, DCT (Discrete Cosine Transform) processing andWavelet transform processing canal so be employed. Also, availableinverse conversion processing is not limited to IFFT processing alone,and other suitable processing including, for instance, inverse DCTprocessing and inverse Wavelet conversion processing can also beemployed.

Radio transmission apparatus 100 and radio reception apparatus 150 ofthe present embodiment can be adopted both in base station apparatusesand mobile station apparatuses for use in mobile communications systemsadopting single carrier frequency domain equalization technology.

Embodiment 2

FIG. 6 is a block diagram showing a configuration of a radiotransmission apparatus according to embodiment 2 of the presentinvention. Radio transmission apparatus 200 of FIG. 6 has the same basicconfiguration as that of radio transmission apparatus 100 described inembodiment 1, and identical components will be assigned the samereference numerals and detailed descriptions thereof will be omitted.Radio reception apparatus 150 described in embodiment 1 can carry outradio communication with radio transmission apparatus 200.

Radio transmission apparatus 200 adopts a configuration which, inaddition to having control section 201 in place of control section 103described in embodiment 1, also has buffer 202 for temporarily storingtransmission signals that have been subjected to IFFT processing, andswitching section 203 which is switched on/off in accordance with aninputted instruction signal and outputs the transmission signals storedin buffer 202, to CP processing section 105.

Control section 201 includes multiplication sections 111 and 112,transmission power control section 113, weighting factor control section114 and propagation path information extraction section 116, which havebeen described in embodiment 1, and further includes weighting factorderiving section 221 that derives, in accordance with a function g(W)that shows the relationship between a PAPR (Peak-to-Average Power Ratio)of the IFFT-processed transmission signal and the weighting factor W,the maximum value of the weighting factor W that makes the PAPR equal toor lower than a value determined in advance by the setting of the radiosection (PAPR set value: 10 dB, for example). Weighting factor derivingsection 211 has peak power detection section 212 that detects a peakpower of the IFFT-processed transmission signal, weighting factorcalculation section 213 that calculates, upon input of a report signalfrom peak power detection section 212, the weighting factor W for usefor transmission power control, in accordance with the above-describedPAPR set value.

Next, a description will be given on the transmission power controloperation in radio transmission apparatus 200 having the aboveconfiguration.

First, in weighting factor calculation section 213, the weighting factorW is temporarily set to the maximum value (i.e., W=1) and then outputtedto weighting factor control section 114. Next, the transmission power ofthe transmission signal is controlled in accordance with thetransmission power control operation described in embodiment 1. Thetransmission signal having its transmission power controlled, issubjected to IFFT processing by IFFT section 104 and then stored inbuffer 202. At this time, the peak power of the IFFT-processedtransmission signal is detected by peak power detection section 212.Then, peak power detection section 212 calculates the PAPR.

Next, the calculated PAPR is compared to the PAPR set value. If theresult of the comparison shows that the PAPR is equal to or lower thanthe PAPR set value, an instruction signal is inputted from peak powerdetection section 212 to switching section 203. In this way, switchingsection 203 is switched to an on-state and the transmission signalsstored in buffer 202 are transferred to CP processing section 105. Areport signal showing that the PAPR is equal to or lower than the PAPRset value is inputted to weighting factor calculation section 213, and,as a result, the value that was set by weighting factor calculationsection 213 is reset to the default value. On the one hand, if theresult of the comparison shows that the PAPR exceeds the PAPR set value,an instruction signal that switches switching section 203 to anoff-state is inputted from peak power detection section 212 to switchingsection 203. With this, switching section 203 is switched to anoff-state. Also, a report signal showing that the PAPR exceeds the PAPRset value, is inputted to weighting factor calculation section 213.

Next, a value smaller than the value that was temporarily set as acandidate for the weighting factor W for use (denoted by “1” in thisdescription), is calculated by weighting factor calculation section 213,in accordance with the inputted report signal. The calculated value isthen outputted to weighting factor control section 114 as the nextcandidate for the weighting factor for use.

In other words, weighting factor deriving section 211, which includespeak power detection section 212 and weighting factor calculationsection 213, calculates the PAPR in association with the candidate forthe weighting factor W. If the PAPR calculated in association with afirst value set as the candidate is equal to or lower than the PAPR setvalue, the first value is set as the weighting factor W. On the otherhand, if the PAPR calculated in association with the first value isgreater than the PAPR set value, a second value, which is smaller thanthe first value, is temporarily set as a new candidate.

The above-described operation is repeated until the peak power detectedby the peak power detection section 212 takes a predetermined value.Accordingly, an optimal weighting factor W can be derived by loopprocessing. Also, a maximum weighting factor W that makes the peak powera predetermined value can be detected, and the value of the peak powercan be controlled. Further, by making the maximum value of the weightingfactor W (W=1) the default value of the candidate, it is possible toefficiently derive the optimal weighting factor W by loop processing.

According to the present embodiment, an increase in the PAPR caused bytransmission power control can be suppressed, so that the efficiency ofthe transmission amplifier of the radio section can be improved.

In the present embodiment, the weighting factor W is set to a commonvalue between frequencies. However, the weighting factor may also be setindividually for each frequency (in other words, a weighting factor Wkassociated with each frequency may be derived).

In the present embodiment, FFT processing is adopted for the processingfor converting a signal in a time domain to a signal in a frequencydomain, and IFFT processing is adopted for the processing for inverselyconverting the signal in the frequency domain to the signal in the timedomain. In addition, applicable conversion processing is not limited toFFT processing alone, and other suitable processing including, forinstance, DCT (Discrete Cosine Transform) processing and Wavelettransform processing can also be employed. Also, available inverseconversion processing is not limited to IFFT processing alone, and othersuitable processing including, for instance, inverse DCT processing andinverse Wavelet transform processing can be employed.

Radio transmission apparatus 200 of the present embodiment can beemployed both in base station apparatus and mobile station apparatusused in mobile communication systems adopting single carrier frequencydomain equalization technology.

Weighting factor deriving section 211, buffer 202 and switching section203 described in the present embodiment can be combined with theconfiguration of radio transmission apparatus 100 described inembodiment 1.

There are cases where the base station apparatus in the above-describedembodiments is referred to as “Node B,” the mobile station apparatus as“UE” and the “subcarrier” as “tone.”

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip.

“LSI” is adopted here but this may also be referred to as “IC”, “systemLSI”, “super LSI”, or “ultra LSI” depending on differing extents ofintegration.

Further, the method of circuit integration is not limited to LSI'S, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of an FPGA (FieldProgrammable Gate Array) or a reconfigurable processor where connectionsand settings of circuit cells within an LSI can be reconfigured is alsopossible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application in biotechnology isalso possible.

The present application is based on Japanese Patent Application No.2004-229733, filed on Aug. 5, 2004, the entire content of which isexpressly incorporated by reference herein.

INDUSTRIAL APPLICABILITY

The radio transmission apparatus and the radio transmission method ofthe present invention are suitable for use in base station apparatusesor in mobile station apparatuses employed in single carrier transmissionsystems with frequency domain equalization.

1. A radio transmission apparatus comprising: a conversion section thatconverts a signal in a time domain to a signal in a frequency domain; acontrol section that controls a transmission power of the convertedsignal in the frequency domain; an inverse conversion section thatinversely converts the transmission power controlled signal to a signalin the time domain; and a transmission section that transmits theinversely converted signal on a single carrier.
 2. The radiotransmission apparatus according to claim 1, wherein the control sectioncomprises a deriving section that derives a coefficient for use forcontrolling the transmission power, in accordance with a function of thecoefficient.
 3. The radio transmission apparatus according to claim 2,wherein the control section further comprises an acquisition sectionthat acquires the function that shows a reception error rate of a radioreception apparatus predicted when the signal having the transmissionpower controlled is transmitted to the radio reception apparatus.
 4. Theradio transmission apparatus according to claim 3, further comprising anextraction section that extracts frequency domain equalization algorithminformation transmitted from the radio reception apparatus, wherein theacquisition section acquires the function in accordance with thefrequency domain equalization algorithm information.
 5. The radiotransmission apparatus according to claim 3, wherein the derivingsection obtains the coefficient that minimizes the reception error rateusing the function.
 6. The radio transmission apparatus according toclaim 2, wherein the deriving section derives the coefficient inaccordance with the function that shows a relationship between thecoefficient and a peak-to-average power ratio of the inversely convertedsignal.
 7. The radio transmission apparatus according to claim 6,wherein the deriving section obtains the coefficient that makes thepeak-to-average power ratio equal to or lower than a predeterminedvalue, in accordance with the function.
 8. The radio transmissionapparatus according to claim 6, wherein the deriving section obtains amaximum value of the coefficient that makes the peak-to-average powerratio equal to or lower than a predetermine value, in accordance withthe function.
 9. The radio transmission apparatus according to claim 6,wherein the deriving section: calculates the peak-to-average power ratioin association with a candidate of the coefficient; when thepeak-to-average power ratio calculated in association with a first valueset as the candidate is equal to or lower than the predetermined value,sets the first value as the coefficient; and when the peak-to-averagepower ratio calculated in association with the first value is greaterthan the predetermined value, sets, as the candidate, a second valuethat is lower than the first value.
 10. The radio transmission apparatusaccording to claim 9, wherein the deriving section sets a predeterminedmaximum value of the coefficient as the default value of the candidate.11. The radio transmission apparatus according to claim 6, wherein thederiving section obtains the coefficient that makes a peak power of theinversely converted signal a predetermined value.
 12. The radiotransmission apparatus according to claim 1, wherein: the single carriercomprises a band including a plurality of frequencies; the radiotransmission apparatus further comprises an extraction section thatextracts propagation path information transmitted from a radio receptionapparatus; and the control section sets the coefficient to a commonvalue among the plurality of frequencies and multiplies the propagationpath information by the value by to obtain a transmission power of theconverted signal.
 13. A radio reception apparatus comprising: aconversion section that converts a signal in a time domain transmittedon a single carrier to a signal in a frequency domain; a determiningsection that determines an algorithm for frequency domain equalizationprocessing to which the converted signal is to be subjected; ageneration section that generates frequency domain equalizationalgorithm information showing the determined algorithm; and atransmission section that transmits the generated frequency domainequalization algorithm information to a radio transmission apparatus.14. A radio transmission method comprising: a conversion step ofconverting a signal in a time domain to a signal in a frequency domain;a control step of controlling a transmission power of the convertedsignal in the frequency domain; an inverse conversion step of inverselyconverting the signal with the transmission power controlled to thesignal in the time domain; and a transmission step of transmitting theinversely converted signal on a single carrier.
 15. A radio receptionmethod comprising: a conversion step of converting a signal in a timedomain transmitted on a single carrier, to a signal in a frequencydomain; a determination step of determining an algorithm for frequencydomain equalization processing to which the converted signal is to besubjected; a generation step of generating frequency domain equalizationalgorithm information showing the determined algorithm; and atransmission step of transmitting the generated frequency domainequalization algorithm information to a radio transmission apparatus.